Anders Emmelin

Diesel exhaust exposure and smoking: A case-referent study of lung cancer among Swedish dock workers

We studied 50 lung cancer cases and 154 matched referents, all dock workers, for whom we obtained smoking information and employment histories. We assessed exposures from information on annual diesel fuel consumption from each of the 15 ports included. We used a smoker/nonsmoker term and three exposure variable (machine time, cumulative fuel, and exposed time with fuel consumption above a minimum cutpoint) in the analyses, with three categories for each exposure variable. Odds ratios (ORs) for medium and high exposure groups are consistently higher than reference (low), with an increasing exposure-response trend that is most marked for the exposed time variable (ORs: low = 1.0; medium = 1.6; high = 2.8). When smoking and that exposure variable are simultaneously included in the analyses, odds ratios for the medium (OR = 2.7) and high (OR = 6.8) levels of exposure increase, as does the odds ratio for smoking. Separating smokers and nonsmokers, with the low exposed nonsmokers as the common reference category, the odds ratios are 1.6 (medium) and 2.9 (high) for the nonsmokers, and 10.7 (medium) and 28.9 (high) for smokers. These results indicate an independent effect of diesel exhaust exposure and a strong interaction between smoking and diesel exhaust.

DSS and DHS: longitudinal and cross-sectional viewpoints on child and adolescent mortality in Ethiopia

BackgroundIn countries where routine vital registration data are scarce, Demographic Surveillance Sites (DSS: locally defined populations under longitudinal surveillance for vital events and other characteristics) and Demographic and Health Surveys (DHS: periodic national cluster samples responding to cross-sectional surveys) have become standard approaches for gathering at least some data. This paper aims to compare DSS and DHS approaches, seeing how they complement each other in the specific instance of child and adolescent mortality in Ethiopia.MethodsData from the Butajira DSS 1987–2004 and the Ethiopia DHS rounds for 2000 and 2005 formed the basis of comparative analyses of mortality rates among those aged under 20 years, using Poisson regression models for adjusted rate ratios.ResultsPatterns of mortality over time were broadly comparable using DSS and DHS approaches. DSS data were more susceptible to local epidemic variations, while DHS data tended to smooth out local variation, and be more subject to recall bias.ConclusionBoth DSS and DHS approaches to mortality surveillance gave similar overall results, but both showed method-dependent advantages and disadvantages. In many settings, this kind of joint-source data analysis could offer significant added value to results.

Magnitude of indoor NO2 from biomass fuels in rural settings of Ethiopia

UNLABELLED Half of the worlds population and about 80% of households in Sub-Saharan Africa depend on biomass fuels. Indoor air pollution due to biomass fuel combustion may constitute a major public health threat affecting children and women. The purpose of this study was to measure levels of indoor NO(2) concentration in homes with under-five children in rural Ethiopia. The study was undertaken in the Butajira area in Ethiopia from March 2000 to April 2002. 24-h samples were taken regularly at about three month intervals in approximately 3300 homes. Indoor air sampling was done using a modified Willems badge. For each sample taken, an interview with the mother of the child was performed. A Saltzman colorimetric method using a spectrometer calibrated at 540 nm was employed to analyze the mass of NO(2) in field samples. Wood, crop residues and animal dung were the main household fuels. The mean (s.d.) 24-h concentration of NO(2) was 97 microg/m(3) (91.4). This is more than double the currently proposed annual mean of WHO air quality guideline. Highland households had significantly higher indoor NO(2) concentration. This study demonstrates high levels of indoor NO(2) in rural homes of Ethiopia. PRACTICAL IMPLICATIONS Respiratory infection is a major cause of morbidity and mortality, globally. Acute respiratory symptoms are also related to high levels of air pollution. Interventions aimed at reducing exposure to indoor air pollution should focus on cooking and heating practices in developing countries. This study is not undermining the role of other biomass smoke constituents in determining respiratory infections.

Sources of variation for indoor nitrogen dioxide in rural residences of Ethiopia.

BackgroundUnprocessed biomass fuel is the primary source of indoor air pollution (IAP) in developing countries. The use of biomass fuel has been linked with acute respiratory infections. This study assesses sources of variations associated with the level of indoor nitrogen dioxide (NO2).Materials and methodsThis study examines household factors affecting the level of indoor pollution by measuring NO2. Repeated measurements of NO2 were made using a passive diffusive sampler. A Saltzman colorimetric method using a spectrometer calibrated at 540 nm was employed to analyze the mass of NO2 on the collection filter that was then subjected to a mass transfer equation to calculate the level of NO2 for the 24 hours of sampling duration. Structured questionnaire was used to collect data on fuel use characteristics. Data entry and cleaning was done in EPI INFO version 6.04, while data was analyzed using SPSS version 15.0. Analysis of variance, multiple linear regression and linear mixed model were used to isolate determining factors contributing to the variation of NO2 concentration.ResultsA total of 17,215 air samples were fully analyzed during the study period. Wood and crop were principal source of household energy. Biomass fuel characteristics were strongly related to indoor NO2 concentration in one-way analysis of variance. There was variation in repeated measurements of indoor NO2 over time. In a linear mixed model regression analysis, highland setting, wet season, cooking, use of fire events at least twice a day, frequency of cooked food items, and interaction between ecology and season were predictors of indoor NO2 concentration. The volume of the housing unit and the presence of kitchen showed little relevance in the level of NO2 concentration.ConclusionAgro-ecology, season, purpose of fire events, frequency of fire activities, frequency of cooking and physical conditions of housing are predictors of NO2 concentration. Improved kitchen conditions and ventilation are highly recommended.

Patterns of local migration and their consequences in a rural Ethiopian population

Aims: In the context of the Butajira Rural Health Programme (BRHP) in Ethiopia, which has maintained demographic surveillance in selected communities since 1987, this paper investigates patterns of migration and their consequences within that population over a ten year period 1987-1996. Methods & Results: Based on observations of over 336,000 person-years in nine rural villages and one small town, 48% of individuals migrated in or out of the study area at some stage, as recorded in monthly household visits. There was a net incidence of migration into the urban area, particularly among young adults. Mortality was higher among residents compared with in-migrants, with rates of 10.5 (95% CI 7.5 to 14.9) and 8.2 (95% CI 5.8 to 11.7) per 1,000 person-years respectively after adjustment for age, sex and area of residence, a rate ratio of 1.3. Fertility among in-migrant and resident women was similar, at rates of 0.26 and 0.28 births per reproductive year respectively. Conclusions: The causes of the observed differences in mortality are not clear, though they may be partly due to self-selection effects among migrants, and may have important implications for future health policy and planning in Ethiopia and other similar settings.

A rural Ethiopian population undergoing epidemiological transition over a generation: Butajira from 1987 to 2004:

Aims: To describe the epidemiological development of a rural Ethiopian population from 1987 to 2004 in terms of mortality and associated sociodemographic factors. Methods: A rural population comprising 10 communities was defined in 1987 and has since been followed by means of regular household visits. After an initial census, births, deaths and migration events were recorded, together with key background factors, on an open cohort basis. Over 97,000 individuals were observed during a total of over 700,000 person years. Results: The initial population of 28,614 increased by an average of 3.64% annually to 54,426 from 1987 to 2004, and also grew older on average. Birth and mortality rates fell, but were still subject to short-term variation due to external factors. Overall mortality was 13.5 per 1000 person years. Increasing mortality in some adult age groups was consistent with increasing AIDS-related deaths, but a new local hospital in 2002 may have contributed to later falls in overall mortality. Sex, age group, time period, literacy, water source, house ownership and distance to town were all significantly associated with mortality differentials. Conclusions: This population has undergone a complex epidemiological transition during a generation. Detailed long-term surveillance of this kind is essential for describing such processes. Many factors that significantly affect mortality cannot be directly controlled by the health sector and will only improve with general development.

Vulnerability to episodes of extreme weather: Butajira, Ethiopia, 1998 - 1999

Background: During 1999–2000, great parts of Ethiopia experienced a period of famine which was recognised internationally. The aim of this paper is to characterise the epidemiology of mortality of the period, making use of individual, longitudinal population-based data from the Butajira demographic surveillance site and rainfall data from a local site. Methods: Vital statistics and household data were routinely collected in a cluster sample of 10 sub-communities in the Butajira district in central Ethiopia. These were supplemented by rainfall and agricultural data from the national reporting systems. Results: Rainfall was high in 1998 and well below average in 1999 and 2000. In 1998, heavy rains continued from April into October, in 1999 the small rains failed and the big rains lasted into the harvesting period. For the years 1998–1999, the mortality rate was 24.5 per 1,000 person-years, compared with 10.2 in the remainder of the period 1997–2001. Mortality peaks reflect epidemics of malaria and diarrhoeal disease. During these peaks, mortality was significantly higher among the poorer. Conclusions: The analyses reveal a serious humanitarian crisis with the Butajira population during 1998–1999, which met the CDC guideline crisis definition of more than one death per 10,000 per day. No substantial humanitarian relief efforts were triggered, though from the results it seems likely that the poorest in the farming communities are as vulnerable as the pastoralists in the North and East of Ethiopia. Food insecurity and reliance on subsistence agriculture continue to be major issues in this and similar rural communities. Epidemics of traditional infectious diseases can still be devastating, given opportunities in nutritionally challenged populations with little access to health care.

From birth to adulthood in rural Ethiopia: the Butajira Birth Cohort of 1987.

Long-term birth cohorts from developing countries are uncommon. Here a unique birth to 18-years cohort based on all births during 1987 in a rural area of Ethiopia is presented. This was the first year of the ongoing Butajira Rural Health Programme, since when the sampled population has been followed up in regular household visits. A total of 1884 livebirths in 1987 formed the cohort, corresponding to a birth rate of 0.31 per woman per year; the male : female ratio was 1.10. Perinatal mortality was 22 per 1000 livebirths, and infant mortality 65 per 1000 livebirths. Survival from birth to 18 years was 760 per 1000. Living in Butajira town had a considerable survival advantage compared with the surrounding villages. Most deaths were due to infections. Four per cent of the cohort experienced the death of their mothers before the age of 18 years, and 15 of the girls delivered their own children, suggesting that 1 in 25 women may bear a child before their eighteenth birthday in this community. The children in the cohort received no consequent special care or attention, and so they probably accurately represent the harsh realities of growing up in rural Ethiopia at the turn of the Millennium. The huge gaps between their experience and that of their contemporaries in more affluent settings are a scandal of the 21st century.

Spatio-temporal clustering of mortality in Butajira HDSS, Ethiopia, from 1987 to 2008

Background: Mortality in a 1 1The Deputy Editor Peter Byass, has not had any part in the review and decision process for this paper.population may be clustered in space and time for a variety of reasons, including geography, socio-economics, environment and demographics. Analysing mortality clusters can therefore reveal important insights into patterns and risks of mortality in a particular setting. Objective and design: To investigate the extent of spatio-temporal clustering of mortality in the Butajira District, Ethiopia, from 1987 to 2008. The Health and Demographic Surveillance System (HDSS) dataset recorded 10,696 deaths among 951,842 person-years of observation, with each death located by household, in which population time at risk was also recorded. The surveyed population increased from 28,614 in 1987 to 62,322 in 2008, in an area approximately 25 km in diameter. Spatio-temporal clustering analyses were conducted for overall mortality and by specific age groups, grouping the population into a 0.01° latitude–longitude grid. Results: A number of significantly high- and low-mortality clusters were identified at various times and places. Butajira town was characterised by significantly low mortality throughout the period. A previously documented major mortality crisis in 1998–1999, largely resulting from malaria and diarrhoea, dominated the clustering analysis. Other local high-mortality clusters, appreciably attributable to meningitis, malaria and diarrhoea, occurred in the earlier part of the period. In the later years, a more homogeneous distribution of mortality at lower rates was observed. Conclusions: Mortality was by no means randomly distributed in this community during the period of observation. The clustering analyses revealed a clear epidemiological transition, away from localised infectious epidemics, over a generation. Access the supplementary material to this article: animated graphic – sequence.ppsx – displaying the clusters (viewed over time) shown in Table 1 (see Supplementary files under Reading Tools online).